When congestion occurs in a cell of a mobile communication system or in a communication network apparatus, a base station can avoid a congestion state, for example, by barring user equipment being in an idle mode from accessing the base station, and transferring the user equipment to another cell. The user equipment camping on a cell can be transferred to another cell by using system information which is included in broadcast information transmitted from a base station. For example, the system information may include state information indicating a state of the cell, and the state information may indicate whether the cell is congested. In general, the system information includes an information element which is required for user equipment to properly operate in a cell. For a case of a mobile communication system, such as an LTE system, an information element “cellBarred IE” may be used as the state information indicating the state of the cell. When congestion does not occur, the information element takes a value of “notBarred.” When the congestion occurs, the information element takes a value of “Barred.” In this manner, by broadcasting, as the system information, the state information indicating whether the congestion occurs, the user equipment can determine whether it is barred. Non-Patent Document 1 discloses such a technique.
Related Art Document
[Non-Patent Document]
Non-Patent Document 1: 3GPP TS36.304 V8.9.0(2010-09), 5.2.4, and 5.3